As representative image display devices, liquid crystal display devices are exemplified. The liquid crystal display device includes a liquid crystal panel composed of a transparent electrode, a liquid crystal cell in which a liquid crystal is filled and sealed between glass substrates having a pixel pattern or the like formed on a surface thereof and having a thickness of about 1 mm via a gap having about several microns, a polarizing plate stuck on each outside surface thereof, and a light source such as a backlight system, etc.
The polarizing plate configuring this liquid crystal panel is thin and easily scratched, and therefore, in particular, in mobile phones, game machines, digital cameras, onboard applications, and the like, liquid crystal display devices having a structure in which a transparent front plate (protective panel) is provided leaving a specific space on the front surface of the liquid crystal panel are generally used.
Furthermore, in recent years, in mobile phones, game machines, digital cameras, onboard parts, notebook computers, desktop computers, computer monitors, and the like, touch panels have been mounted. In the case of such a liquid crystal display device, a laminate structure in which a protective panel, a touch panel, and a liquid crystal panel are laminated in this order is adopted, and a specific space is existent between the protective panel and the touch panel and between the touch panel and the liquid crystal panel, respectively.
In the case where the space in the above-described liquid crystal display device is air, this space is a cause of generating scattering of light. Owing to this, the contrast, luminance, or transmittance is lowered, and furthermore, a lowering of the image quality may possibly occur due to ghost.
As a method of preventing such scattering of light, PTL 1 proposes a method of filling an oily material in a space between a protective panel and a liquid crystal panel; and PTL 2 proposes a method of allowing a sheet obtained by copolymerizing an acrylic monomer to intervene between a protective panel and a liquid crystal panel.
In addition, in a plasma display panel (PDP) that is one of flat panel displays (FPD), in order to prevent cracking of PDP, a space of from about 1 to 5 mm far from PDP is provided, and a protective panel having a thickness of about 3 mm, such as glass, etc., is provided on the front surface (viewing surface side).
As a method of preventing such cracking of display or preventing such scattering of light or the like, PTLs 3 and 4 propose a method of allowing an optical film composed of a specified resin to intervene in a space between a protective panel and an image display unit such as a plasma display plate, a liquid crystal panel, etc., a space between a protective panel and a touch panel, and a space between a touch panel and an image display unit (hereinafter also collectively referred to as “space between a protective panel and an image display unit or the like”).